Distorted bearing piezoelectric voltage source



1953 G. H. HUFVFERD ETAL 3,101,420

DISTORTED BEARING PIEZOELECTRIC VOLTAGE SQURCE Filed Nov. 6, 1961 2 Sheets-Sheet 1 53 INVENTORS 40 GEORGE H. HUFFERD ROBERT H. JOSEPHSON ALFRED L..W.WILLIAMS 2c FIG.3 BY

ATTORNEY Aug. 20, 1963 G. H. HUFFERD ETAL 3, 0

DISTORTED BEARING PIEZOELECTRIC VOLTAGE SOURCE Filed Nov. 6, 1961 z Sheets-Sheet 2 8 max Am EE O WEH W m WW A HJW 7 H H J b 6 w 5 s I .i. GRA WW G F 4 u l s F m a u w United States Patent 3,101,420 DISTORTED BEARlNG PIEZOELECTRHI VOLTAGE SOURCE George H. Hutierd, Lyndhurst, Robert H. Josephson,

Cleveland Heights, and Alfred L. W. Williams, Cleveland, Ohio, assignors to Clevite Corporation, a corporation of ()hio Filed Nov. 6, 1961, er. No. 150,534 19 (Claims. (Cl. Mil-8.7)

This invention relates to improvements in piezoelectric voltage source devices and, particularly, to improvements in the mechanism for squeezing a piezoelectrically responsive ceramic or crystal element used in such devices.

An object of the present invention resides in the provision of a voltage source of the character indicated which employs a low friction distorted radial bearing to alternately squeeze and release an element piezoelectrically responsive in compression to generate an electric potential.

A further object of this invention resides in the provision of a distorted bearing actuator for piezo electric devices in which the area of stress or load application is comparatively larger than in devices known in the prior art. The objective is to effect a reduction in actuator wear and, moreover, a reduction in actuation load on the stress area to reduce metallurgical qualitative requirements of the stressed or actuated member.

A further object resides in the provision of a voltage source of the character indicated which is particularly suited for use as a spark generator in a multi-cylindcr engine ignition system and can provide 2, 4, 6, 8 or more electric potentials at engine camshaft speed.

A further object resides in the provision of a voltage source which can provide a continuous electric potential in the form of steady state high voltage alternating current, whereby the need of a transformer is obviatedin many applications.

.A still further object of this invention resides in the provision of a device which can be used in association with an engine ignition system to manually control the point of maximum compression of the piezoelectric element relative to the position of the piston in the engine.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings:

FIGURE 1 is a plan view partly in section of a distorted bearing voltage source taken along line 1-1 of FIGURE 2;

FIGURE 10 is a detailed shown in FIGURE 1;

FIGURE 2 is a longitudinal sectional view taken along line 2-2 of FIGURE 1; t

. FIGURE 3 is a plan View of a modified voltage source shown partly in section taken along line 3-3 of.FIG- URE 4;

FIGURE 4 is a longitudinal sectional view taken along line 4-4 of FIGURE 3;

FIGURE 5 is a longitudinal sectional view of a modified piezoelectric voltage source;

FIGURE 6 is a view similar to FIGURE 5 illustrating still another modification of the piezoelectric voltage source; and

FIGURE 7 is a diagrammatic view of operation embodied in FIGURE 6.

An aspect of the present invention resides in the provision of a piezoelectric voltage source which comprises a radial bearing including a first and a second bearing race having \a common axis and adapted for relative rotation, the first race being distorted and the second plan view of a component of the principle 7 terial to permit radial load transmittal.

race being distortable out-of-round relative to the axis; and piezoelectric element means mounted in load transmitting engagement with the second race whereby, upon relative rotation between the races, a load established by the distortion is applied to the piezoelectric element to generate a voltage.

Referring now in greater detail to the drawings, where in similar reference characters designate corresponding parts throughout, there is shown, in FIGURES 1 and 2, a piezoelectric voltagesource 1. The voltage source 1 includes a rolling contact radial bearing 2 comprised of an annular inner race 3 and an annular outer race 5, the races being coaxially disposed relative to each other. In the preferred embodiment the inner and outer races 3, 5 are preferably formed of flexible metallic material. Each annular race provides a bearing surface radially spaced from the common axis of the races 3, 5. Rollably interposed between the annular inner and outer races are a plurality of ball bearings 7 which are suitably restrained between the races to insure a low friction engagement when relative rotation between the inner and the outer race takes place.

A distorting ring 9 circumferential-1y surrounds the outer race 5 for distorting the bearing races out-of-round relative to the common axis thereof. The distorting ring 9 is formed of rigid material having an inside diameter which is slightly larger than the outside diameter of the outer race 5. A set screw '11 extends radially through the ring 9 and engages the outer race 5. The above noted distortion of the outer race is established by advancing the set screw 11 against the outer race until the outer race has taken on an out-of-round configuration of predetermined proportions.

The position of the set screw 11 thus fixes the out-ofround distortion of the normally annular outer race 5. In the distorted condition the races are shaped so that the smallest diameter is in a radial plane extending through the central axis and the center portion of the set screw 11 The largest diameter across the bearing is located at an angle of about degrees relative to the location of the smallest diameter. Since the inner race 3 is constructed of flexible material and the ball bearings are interposed between the inner and outer races, the inner race is distorted out of-round to the same degree as the outer race.

Mounted coaxially within the inner race 3 is a piezoelectric element -13 in the form of a circular disc having a central aperture 14. The space defined by aperture 14 is filled by a rigid conducting member 23 constructed of electricity conducting material. A narrow circular opening 25 in member 23 is adapted to receive a terminal or cable 27. The outer faces of the disc 13 are protected by plastic top and bottom cover-s 15a, 15b having insulating qualities. The top cover 15a has. an axial projection 16 which surrounds member 2 3', and a central opening 24 in the top cover registers with opening 25. The bottom cover 15b is interposed between the piezoelectric element 13 and a support flange 19'. The flange 19 is integrally connected with rotatable shafit 21. An annular sleeve 17 is disposed with a press fit between the outer radial surface of element 13' and the inner race, one axial end of the sleeve is securely connected to the radial surtace of support flange 19, and the other end forms a radial flange18 which overlaps and abuts the top cover 15a. The sleeve 17 thus serves to maintain the covers 15a, 15b in place, and establishes a rigid connection between the shaft 21 and the element 13 so that when the shaft is rotated, the disc 13', the sleeve 17' and the inner race 3 rotate in unison with shafit 21 while the outer race 5 and the distorting ring 9 are held stationary by means not shown. The sleeve 17 is constructed of flexible ma- The piezoelectricdisc 13 may be composed of crystal elements or piezoelectrioally responsive ceramics. Preferably, the disc is comprised of polycrystalline ceramic material such as :barium titanate, lead titanate-zirconate or the like, and includes a plurality of circular sectors 13a, 13b, 13c and 13d which have been polarized in alternate directions as hereafter described.

The element 13 is polarized to be piezoelectrically responsive. More particularly, see FIGURE 1a, sections 13a and 130 are polarized by connecting, for instance, a positive terminal of the poling supply (not shown) to electrodes 26a, 26s on the inner circumference and a negative terminal to electrodes 28a, 28c on the outer circumference of the element 1 3. The adjoining circular sectors 13b and 13d are both polarized in the opposite direction, that is, with the negative terminal of the poling supply connected to electrodes 26b, 26d on the inner circumference and the positive terminal to electrodes 28b, 28d on the outer circumference.

For pol ing it is necessary to have all electrodes separated. It is not necessary after the poling operation to keep electrodes on the inner circumference (26) or the electrodes on the outer circumference (28) separated, as the piezoelectrically generated electric fields are parallel (not antiparallel) in all four sectors.

As aforestated, the element 13 is placed within sleeve 17 and the latter is suitably secured within the inner trace 3. The adjusting screw 11 is forced against the outer race to force an out-:of-round condition of the inner and outer races, the sleeve and the piezoelectric disc. This pressure, imposed upon the piezoelectric element, is effective to place sections 13a and 13c under compression in the radial direction and sections 13d and 13b under tension in the radial direction. For this case, with poling fields as described in the preceding paragraph, the piezoelectrically generated field is uniform in a radial direction, with negative charges on the outer electrode (28), and positive charges on the inner electrode (26). The electrodes 28a d on the outer circumference are connected together by contact with sleeve 17 to form one terminal which is grounded. The electrodes 26a a: on the inner circumference are also connected together by virtue of their contact with member 23. With 90 degrees of rotation sectors 13d and 13b are under compression and sectors 13a and 13c are under tension, causing a reversal of the generated piezoelectric voltage. Further reversals take place with each 90 degrees of rotation, thus forming as the disc rotates a steady state alternating current, with two complete voltage cycles for each revolution of the shaft 21..

Those versed in the art will appreciate that relative ro tation between the races can be established by rotating only the inner race as aforedescribed or, alternatively, by rotating. the outer race and the distorting ring 9, only, or by rotating the inner and outer races in opposite directions. Counter-rotating the races is effective to convert, theoretically, a two-lobed arrangement to a fourl obed device by driving, for example, the outer race at the same rotational speed as the inner race, but in the opposite direction.

In "an engine application where the invention is used in an ignition system for spark firing and shaft 21 is driven in timed relation to the rotation of an engine camshaft, manual control of the point of maximum compression of piezoelectric element 13 relative to the position of the piston in the engine (neither are shown) can readily 'be established to advance or retard the spark firing by turning the normally stationary outer race in one direction or the other relative to the shaft 21.

FIGURES 3 and 4 illustrate a modified piezoelectric voltage source which utilizes a distortable rolling contact radial bearing 2a to apply a compressive stress to piezo-- electric element 4-0.

More particularly, in this embodiment the bearing 2a comprises an outer race 5a and an inner race is constituted 4 by sleeve 17a. Roller bearings 36 are placed between sleeve 17a and outer race 5a obviating the need of a separate inner race.

A round mounting base 38 is placed coaxially within sleeve 17a without engaging the inner surface of the sleeve 17a. The base 38 is suitably supported by and connected to support member 19a of shaft 21a. The base is formed of rigid material and provides a chordally extending slot 39' (not visible as such) to receive in the slot the piezoelectric element 40 and protective enclosures 52, 53 and 54 hereafter further described. The piezoelectric element 40: is comprised of two separate cylindrical elements 40a and 40b mounted end-to-end and manufactured of polycrystalline ceramic material "of the type above described.

The piezoelectric elements Ma and 4011 during manufacturing are suitably polarized to be piezoelectrically responsive in compression, and are electroded and electrically grounded so that upon application of a compressive force a high voltage potential is generated. The two elements 40a and 40 h are mechanically in series and electrically in parallel by being mounted with the like poles to the center. To facilitate a proper electrical conmotion with terminal 27a there is disposed between the ceramic elements 40a and 40b a plurality of thin aluminum discs 42. The outer end faces of ceramic elements 40a and 40 h abut aluminum discs 44 and '46, respectively, to provide electrical ground connection for the piezoelectric elements and to complete the electrical circuit.

Each element 40a, 40b is suitably enclosed by a protective cylindrical sleeve 52, 53, respectively, of moisture resistant insulating material. A protective plastic housing 54- having electrical insulating qualities suitably encloses the elements 40a and 4%, including sleeves 52, 53 surrounding the elements. The plastic housing '54 has, adjacent to the aluminum discs 42,, a narrow bore 56 and a collar 58, see FIGURE 4, to receive the terminal 27a which is inserted through bore 56.

The discs 4c, 4'4 and 46 serve to uniformly distribute the compressional forces acting upon the elements 40a, 40b to insure symmetrical alignment of the mechanical axis with respect to the electrical axis of the piezoelectric elements.

A heavy metal end plate 48 is disposed in slot 3 9 between disc 44 and sleeve 17a (inner race) and a similar plate 50 is interposed between disc 46 and the sleeve, both plates '48 and 5t) engage the sleeve 17a at diametrically opposed ends. 7 i

The diameter across the outer radical faces of metal plates 48 and 50 is greater than the diameter of the mount ing base 38 so that the plates protrude radially outward to form shoulders positioned to transmit loads.

In operation the device functions in the same manner as the device previously described. Rotation of shaft 21a establishes relative rotation between the sleeve 17a and the outer race 5a. The distortion ring 9a maintains the outer race 5a in \a fixed out-of-round condition. The shape of sleeve 17a is, by virtue ofengagement with roller bearings 36, parallel to that of the outer race. Again, the radial distance between any given point on the outer circumference of the sleeve 17a and the central axis varies during circumferential progression of sleeve 17a since the distortion of the sleeve is not fixed. This variation in the radial distance establishes a load which is applied to the plates 46 and 48 which transmit this load onto elements 40a and 40b and a high voltage electric potential is generated at the point of maximum compression. Upon rotating base 38 further relative to the outer race, the compression upon the elements is gradually released with the complete release occurring approximately degrees relative to the point of maximum compression or squeezing action whereupon another electric potential is generated.

The device is thus capable of generating four electric potentials per revolution which are releasable through terminal 27a.

FIGURE 5 is another modification of the principal device embodying the same basic features of above described devices. A hollow housing 60 is coaxially disposed with respect to the inner and outer races 3b and 5b, respectively, and is constructed integral with shaft 21b.

A single piezoelectric element 400 is mounted longitudinally in the housing and is suitably enclosed by a protective sleeve 53a and a housing 54a composed of insulating material.

Abutting one end face of the element 400 is an aluminum disc 44:: which constitutes the hot side of the piezoelectric element. Longitudinal displacement of the element is prevented by a threaded plug 62 detachably inserted in housing 60. The space between disc 44a and the plug 62 is filled by a heavy metal end piece 48a. The plug may also be used to pre-load the piezoelectric element. Abutting' the other end face of the element 400 is a second aluminum disc 46a which serves as a ground connection.

The housing includes two radially extending and oppositely located cylindrical load transmitting plungers 64 and 66. ',The outer radial ends of the plungers engage the inner periphery of the inner race 31) and the opposite ends of plungers 64, 66 are illustrated extending slightly into a hollow chamber 68 which is filled with hydraulic means 69, such as rubber; the rubber is in operative load applying engagement with the ceramic element.

In thefree (unstressed) condition the outer radial ends protrude beyond the cylindrical periphery of the housing 60 and, upon relative rotation between inner and outer races 3b, 5b, the plungers are displayed radially toward and into the hydraulic means 69. A hydraulic effect is established by forcing the plungers into the rubber. That is to say, the rubber is forced against the piezoelectric element compressing the latter along its longitudinal axis, whereby the piezoelectric element generates an electric potential. Upon release of the compressive force acting against the element 40c, a second electric potential is generated. A further description is contained in co-pending application U.S. Serial No. ;183,830, assigned to the same assignee as the instant application.

The voltage source 1d shown in FIGURE 6 is a further modification of the basic device and FIGURE 7 illustrates diagrammatically an exaggerated three-lobed cam to facilitate better perception of this embodiment. Prime marks are affixed to the numbers to identify the corresponding components that are hereafter described.

The voltage source 1d includes a hollow housing 60a connection therewith. Abutting one outer end of element 40d is a heavy metal plate 48b which is held in position by a pre-load and adjustment screw 78. The screw 78 comprises a cap 80 having a centrally located threaded bore 82 and providing a threaded female extension 84 which mates with end portion 86 of housing 50a. A threaded stem 38 is carried in bore 82 and an end portion thereof protrudes beyond the bore and engages the heavy metal plate 48b. The force with which stem 88 acts against the plate 48b can be adjusted to suit operational pre-loading requirements.

Another heavy metal plate 46b abuts the element 40d at the other end thereof. The metal plate 46b is partly dome-shaped to facilitate uniform load application.

An elongated load transmitting plug 90' is slidably disposed in bore 76 and fits tightly into the space bet-ween the outer race 50 and the heavy metal plate 4612.

In the preceding description relating to FIGURES 1 to 5 the inner race was distorted by loading the outer race. In the present embodiment the outer race 5c is deformed upon relative rotation between the outer race and the cam-shaped inner race by virtue of the out ofround condition of the inner race. In operation the outer race remains stationary and as the inner race rotates having a permanent substantially circular chamber 72 and a longitudinally extending chamber 74; thelatter chamber is located radially with respect to chamber 72. A radially extending connecting bore 76 is located in the housing 60a between chambers 7-2 and 74.

In the circular chamber '72 are coaxially disposed a cylindrical outer bearing race 50 formed of flexible material and a cam-shaped inner race 30. The inner race 3c is connected to a rotatable shaft (not shown) so that the inner race can be rotated to establish relative rotation between the inner and the outer. races. The shape of this inner race may be two-lobed, three-lobed, four-lobed or more, depending upon the use to which it may be put. The inside diameter of the circular chamber 72 is slightly larger than a circle which would exactly circumscribe the high points of the outer race 50. The high points or lobes are equidistantly distributed about the center of the cam, in actual practice the distance from the high point will be approximately :O lO inch greater than the distance from the low pointto the center. To avoid excessive friction, ball bearings 7a are interposed between the inner and the outer race. a

The chamber 74 carries a longitudinally extending piezoelectric element 40d and a plastic housing 54b of the type shown in FIGURES 3 and. 4 and as described in it produces as many squeezing and releaseing cycles as there are lobes on the inner race by forcing the load transmitting plug against the element 40d compressing the latter longitudinally. A two-lobed cam can provide four sparks per revolution which can fire a four cylinder engine at camshaft speed; a three-lobed cam can provide six sparks per revolution which can fire a six cylinder engine at camshaft speed; a four-lobed cam can provide eight sparks per revolution which can fire an eight cylinder engine at camshaft speed, bearing in mind that at lobe position the element 4% is under compression and at mid-point between the lobes the element is completely released, thereby establishing as aforementioned two sparks per cycle, one at high spot of lobe and the other at low spot which is about half distance between lobes.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. A piezoelectric voltage source comprising, in combination: a radial bearing including a first and a second bearing race having a common axis and adapted for relative rotation, said first race being distorted out-0fround and said second race being distortable outof-round relative to said axis; and piezoelectric'element means mounted in load transmitting engagement with said distortab'le second race whereby upon relative rotation between said races a load, established by distorting said second race, is applied to said piezoelectric element means to generate a voltage.

'2. A piezoelectric voltage source according to claim 1, wherein said races are concentrically mounted and said first race constitutes the outer race thereof.

3. A piezoelectric voltage source according to claim 1, wherein said races are concentricallymounted and said second race constitutes the inner race thereof.

4. A piezoelectric voltage source according to claim 2, wherein said outer race has a permanent out-of-round con-figuration and said second race is formed of flexible material.

5. A piezoelectric voltage source comprising, in combination: a radial bearing including an inner and an outer beaming race concentrically mounted and adapted for relative rotation, said inner race having a permanent outof-round configuration, and said outer race being formed of flexible material and distortable relative to the common axis of said races; and piezoelectric element means mounted in load transmitting engagement with said outer race, whereby upon relative rotation between said races a load, established by distorting said outer race, is applied to said piezoelectric element means to generate a voltage.

6. A piezoelectric voltage source comprising, in combination: a radial bearing including, a first and a second bearing race having a common axis and adapted for relative rotation, said races being formed of flexible material and distortable out-of-round relative to said axis; and piezoelectric element means mounted in load transmitting engagement with one of said races, whereby upon relative rotation between said races a load, established by distorting one of said races, is applied to said piezoelectric element means to generate a voltage.

7. A piezoelectric voltage source accordingto claim 6, and distorting means engaging one of said races to distort the race out-of-round relative to said common axis.

8. V A piezoelectric voltage source according to claim 7, and adjusting means operably associated with said distorting means to vary the degree of distortion of the last named race relative to said axis.

9. A piezoelectric voltage source comprising, in combination: a radial bearing including a first and a second bearing race having a common axis and adapted for relative rotation, said first race being distorted and said second race being distort-able relative to said common axis; and means piezoelectrically responsive in compression and coaxially mounted with respect to said axis and in load transmitting engagement with said distortable second race, said means being polarized in a direction extending radially relative to said axis, whereby upon relative rotation between said races a load, established by distorting said second race, is applied to said piezoelectric element to generate a voltage.

10. A piezoelectric voltage source comprising, in combination: a radial bearing including a first and a second bearing race having a common axis and adapted for relative rotation, said first race being distorted and said second race being distortable relative to said common axis; and means piezoelectrically responsive in compression and radially mounted with respect to said axis and in load transmitting engagement with said distortable second race, said means being polarized in a direction extending radially relative to said axis, whereby upon relative rotation between said races a load, established by distorting said second race, is applied to said piezoelectric element to generate a voltage.

11. A piezoelectric voltage source comprising, in combination: a radial bearing including a first and a second bearing race having a common :axis and adapted for relative rotation, said first r-ace being distorted and said second race being distortable relative to said common axis; and means piezoelectrically responsive in compression and coaxially mounted with respect to said axis and in load transmitting engagement with said distortable sec ond race, said means being polarized in a direction coaxial relative to said axis, whereby upon relative rotation between said races a load, established by distorting said second race, is applied to said piezoelectric element to generate a voltage.

12. A piezoelectric voltage source comprising, in combination: a radial bearing including a first and a second bearing race having a common axis and adapted for relative rotation, said first race being distorted and said second race being distortable relative to said common axis; and means piezoelectrically responsive in compression and chordally mounted with respect to said axis and in load transmitting engagement with said distortable second race, said means being polarized in a direction extending chordally relative to said axis, whereby upon relative rotation between said races a load established by distorting said second race is applied to said piezoelectric element to generate a voltage.

13. A piezoelectric voltage source comprising, in combination: a rolling contact radial bearing including an inner and an outer race having a common axis and adapted for relative rotation, said inner and outer races being formed of flexible material and distortable relative to said axis; a distorting ring circumferentially surrounding said outer race for distorting said races relative to said axis; and piezoelectric element means in the form of a circular disc having a central aperture and comprising a plurality of circular sectors, said sectors being polarized in a direction alternately from the outer circumference of said disc radially toward the inner circumference thereof and the adjacent sector being polarized radially. from the inner circumference toward the outer circumference thereof, said disc being coaxially mounted with respect to said inner and outer races for load transmitting engagement with one of said races, whereby upon relative rotation of the races a load, established by distorting said races relative to said axis, is applied to said piezoelectric disc to generate a voltage.

14. A piezoelectric voltage source according to claim 13, wherein said element means is comprised of at least four circular sectors, at least-two 'of said circular sectors being polarized in a direction extending from the outer circumference of said circular disc'radially toward said inner circumference thereof, and the remaining two circular sectors being polarized in a direction extending from the inner circumference of said circular disc radially toward said outer circumference thereof.

15. A piezoelectric voltage source according to claim 13, wherein said element means is comprised of an even number of circular sectors, half of the number of said sections being polarized in a direction extending from the outer circumference of said circular disc radially toward said inner circumference thereof, and the remaining sectors being polarized in a direction extending from the inner circumference of said disc radially toward said outer circumference thereof.

16. A piezoelectric voltage source comprising, in combination: a rolling contact radial bearing means including an inner and an outer race having a common axis and adapted for relative rotation, said inner and outer races being formed of flexible material and distortable relative to said axis; a distorting ring circumferentially surrounding said outer race for distorting said races relative to said axis; and an elongated piezoelectric element means having first and second end faces, said element means being chordally mounted relative to said inner race and said first and second end face thereof being restrained by said inner race to prevent its movement, whereby upon said relative rotation of said races a load, established by distorting said races relative to said axis, is applied to said piezoelectric element means to generate a voltage.

17. A piezoelectric voltage source comprising, in combination: a rolling contact radial bearing means including aninner and an outer race disposed about a common axis and adapted for relative rotation, said inner and outer races being formed of flexible material and distortable relative to said axis; a distorting ring circumferentially surrounding said outer race for distorting said races relative to said axis; hollow housing means coaxially disposed with respect to said races and rigid against longitudinal expansion; piezoelectric element means having first and second end faces and a longitudinal axis normal thereto, said element means being longitudinally mounted in said housing with said first end face thereof restrained by said housing means to prevent its movement; hydraulic means operably confined within said housing and abutting the second end face of said element means; and load transmitting means disposed in said housing means and one end thereof in engagement with one of said races and the other end being in engagement with said hydraulic means, said transmitting means being effective, upon relative rotation of said races, to displace the hydraulic means to apply a load, established by distorting said races relative to said axis, tosaid piezoelectric element to generate a voltage. v

18. A piezoelectric volt-age source according to claim 16, wherein said inner race surrounds portions of said housing means and said load transmitting means is in" engagement with said inner race.

19. A piezoelectric voltage source comprising, in combination: a rolling cont-act radial bearing including an inner and an outer race disposed about a common axis and I adapted for relative rotation, said inner race having a permanent out-of-round configuration and said outer race being formed of flexible material, said outer race being distortable relative to said axis; hollow housing means at least partly radially disposed with respect to said races and rigid against longitudinal expansion; piezoelectric element means having first and second end faces and a longitudinal axis normal thereto, said element means being longitudinally mounted in said housing with said first end face thereof restrained by said housing means to prevent its movement; and load transmitting means disposed in said housing means and in engagement with said outer No references cited. 

1. A PIEZOELECTRIC VOLTAGE SOURCE COMPRISING, IN COMBINATION: A RADIAL BEARING INCLUDING A FIRST AND A SECOND BEARING RACE HAVING A COMMON AXIS AND ADAPTED FOR RELATIVE ROTATION, SAID FIRST RACE BEING DISTORTED OUT-OFROUND AND SAID SECOND RACE BEING DISTORTABLE OUT-OF-ROUND RELATIVE TO SAID AXIS; AND PIEZOELECTRIC ELEMENT MEANS MOUNTED IN LOAD TRANSMITTING ENGAGEMENT WITH SAID DISTROTABLE SECOND RACE WHEREBY UPON RELATIVE ROTATION BETWEEN SAID RACES A LOAD, ESTABLISHED BY DISTORTING SAID SECOND RACE, IS APPLIED TO SAID PIEZOLELECTRIC ELEMENT MEANS TO GENERATE A VOLTAGE. 